Metallic-vapor-rectifier cathode



April 29, 1930. G UD ET AL 1,756,682

METALLIC VAPOR RECTIFIER CATHODE Filed Jan. 12. 1929 Inremors Arthur Gaudenzi Ernst 0b! Altar/7e Patented Apr. 29, 1930 UNETEB STATES rarest caries ARTHUR GAUIDENZI AND ERNST KOBEL, OF BADEN, SWITZERLAND, ASSIG-NORS TO .AKTIENGESELLSGHAFT BROWN BGVERI & CIR, OF BADEN, SWITZERLAND, AJOINT- STOCK COMPANY OF SWITZERLAND IMETALLIC-VAPOR-BECTIFIER CATHODE Application filed January 12, 1929, Serial No. 832,220, and. in Germany January 14, 1928.

This invention relates to improvements in metallic vapor electric equipment and, more particularly, to the cathode construction of metallic vapor electric current rectifiers.

One of the disadvantages inherent in metallic vapor electric current rectifiers is the phenomena commonly called short circuiting which consists of current flowing between adjacent anodes of the rectifier rather than between an anode and the cathode thereof. The exactco-nditions causing such short circuiting are not clearly understood but it is well known that formation of an excessive amount of metallic vapor, within the rectifier, is one of the conditions conducive to the occurrence of such short circuits. .When excessive amounts of metallic vapor, i. e., amounts greater than necessary to conduct the electric are between the electrodes, are produced, a greater amountof heat transfer surface must be provided to condense the useless excessive quantities of metallic vapor to prevent condensation thereof on the anodes. Such condensation on the anodes forms a cathode spot which leads directly to short circuiting.

Another dificulty in equipment of the character above mentioned is the liability of the arc to excessive movement over the surface of the cathode which produces violent agitation of the same. Any increase in the violence of such agitation tends to heat up the cathode unnecessarily and vaporizes greater portions thereof.

Applicants are aware of the existence of mercury vapor rectifiers in which a layer of solid particles of insulating material is placed on the mercury cathode. Such construction, however, does not attain the desired end, because the arc must strike through the layer of solid insulating material to the mercury cathode thereunder. Rapid movement of the are over the surface of the cathode is, therefore, not prevented but increased, and such structure therefore fails to prevent the formation of an excessive amount of mercury vapor. Further, the usual ignition devices dipping into the mercury cathode cannot be used to ignite the arc because of interference with the insulating material thereon.

It is among the objects of the present invention to provide means, in connection with the cathode of an electric current rectifier, which will prevent rapid movement of the electric are over the surface of the cathode and thereby avoid the formation of an excessive amount of vapor therefrom.

Objects and advantages, other than those above set forth, will be readily apparent from the description and the drawing which shows one embodiment of the present invention.

Referring more particularly to the drawing by characters of reference, indicates the bottom portion of the container forming a portion of an electric current rectifier which is shown, only partially, in cross-section. The bottom portion 5 has an aperture located approximately centrally therein, which aperture is surrounded by a plurality of insulating members 6 extending from the periphery thereof and forming with a cathode plate 7, a recess or well to receive mercury or other suitable material to serve as the cathode of an electric current rectifier. A plurality of anodes 9 extend downwardly from the top of the container (not shown) into proximity with the cathode 8.

The surface of the cathode 8 is covered with metal pieces or chips 10 floating thereon formed of such material as does not form an amalgam with mercury. The cathode spot, that is, the spot at which the arc strikes the cathode, attaches itself to the chips 10 and does not move from the point of attachment or, at most, only very slowly therefrom. The rapic movement of the are over the surface of the cathode and the production of excessive mercury vapor attendant thereon is, accordingly, prevented. The are may be ignited by use of any of the well known dipping, contacting devices.

Although but one embodiment has been illustrated and described, it will be understood that various other embodiments are possible, and that various changes may be made without departing from the spirit of the invention or the scope of the claims.

The invention claimed is:

1. ,In a metallic vapor electric: current re tifier, the combination of anodes, a fluid metallic cathode, a container for said anodes and said cathode, and a layer of metallic chips floating on said cathode.

2. In a metallic vapor electric current rectifier, the combination of anodes, a fluid metallic cathode, a container for said anodes and said cathode, and a layer of metallic chips floating on said cathode, said chips being fo'rmedto prevent amalgamation With said fluid'metallic cathode.

In testimony whereof we have hereunto subscribed our names this 28th day of Decem-V her, A. D. 1928.

ARTHUR GAUDENZI. ERNST KOBEL. 

